The present invention relates to a shoe, especially intended for sporting activity such as ball games, having a sole structure including an insole, a flexible midsole, and an outer sole forming a surface exposed to wear and which, at least at a toe region of the shoe, is molded into a cuplike form. Additionally, an upper of the shoe is, at least in a toe region of the shoe, constructed to form a doubled structure having an inner layer and an outer layer.
The present invention also relates to a method for manufacturing the shoe, according to which the shoe is constructed using a sole structure of which a part is termed the outer sole and is molded into a cuplike form at least in a toe region thereof, and an upper which, at least in the toe region thereof, is constructed as a double upper having an inner layer and an outer layer.
Furthermore, the present invention relates to a blank for a sole intended for use in applying the above-noted method.
It is common for shoes, in tennis and corresponding ball games or athletic activities, to wear out quite rapidly at a forward edge and a top of the toe portion. This is caused by a player dragging a foot along the ground when reaching out for a ball. Recent developments, particularly in the case of tennis courts, include the surfacing of playing areas with fiber felt, asphalt, rubber asphalt, or some other durable surfacing material on which shoes grip excellently. This has partially contributed to increased wear problems on the part of shoes.
Presently, tennis shoes and other footwear intended for use in ball games or athletic activities, are generally constructed utilizing a so-called cup sole structure. In structures of this type, the edge of the sole of the shoe rises upwardly at every point and joins the upper of the shoe. The purpose of the edge on the sole in structures of this type is, particularly at the toe and edge portions of the shoe, to shield the structure from wear. In certain cases, especially when utilizing structures with rubber soles, the sole is attached by stitching in addition to being glued.
An example of a conventional shoe structure of this type is shown in the form of a schematic cross-sectional view in figure A1. Reference numeral 20 in this figure indicates the sole of the shoe, with reference numeral 21 indicating the upper of the shoe. Additionally, the shoe has a flexible midsole 26 and insole 27, as is conventional practice.
The sole 20 of the shoe is constructed to be cuplike in form, by having its edges rise up. This edge is indicated in FIG. A1 at the front end of the shoe by reference numeral 22, and at the rear end of the shoe by reference numeral 23. The upper 21 is glued onto the sole 20 and to the edges 22, 23 of the sole 20. The adhesion is further secured by stitchings which, in FIG. A1, are denoted by reference numerals 24 and 25.
Despite the stitchings, the weakest part of the shoe is the zone where the edge of the sole 20 meets the upper 21. When a player stretches out for a ball with one foot, the shoe on the other foot of the player drags along the surface of the ground, and along the zone noted above. Initially, this leads to wear along the edge of the sole 20, and eventually to the tearing away of the sole 20 from the upper 21 of the shoe.
Structures implementing directly-molded polyurethane soles, are also used presently in shoes intended for use in ball games or other athletic activities. One such structure is shown in the form of a schematic cross-sectional view in FIG. A2. A shoe of this type has a highly wear-resistant elastomer layer denoted by reference numeral 30 in FIG. A2, as the outermost layer of the sole. The sole proper is molded out of foamy, flexible polyurethane denoted by reference numeral 32 in FIG. 2. The upper 31 of the shoe is attached to the sole 32 by gluing. Due to the limitations by manufacturing techniques, the elastomer layer 30 which serves as the wearing surface cannot be made to extend to the upper edge of the toe of the shoe. Instead, a strip of flexible sole material 32 remains exposed between the elastomer layer 30 and the upper of the shoe 31, as illustrated in FIG. A2.
The weakest part of the structure in shoes of this type is also in the toe. As soon as the material of the sole proper 32 at the toe of the shoe, namely between the upper 31 and the outermost layer 30, has worn away, then the edge of the elastomer layer 30 functioning as the wearing surface begins to peel off, following which the shoe is soon in a state of disrepair.
Steps have recently been taken to reinforce the front edge of the above-noted shoes with polyurethane soles. One such solution is illustrated in the form of a schematic cross-sectional view in FIG. A3, illustrating the toe portion of the shoe. A structure of this type of shoe corresponds in principle to the structure illustrated in FIG. A2. Thus, there is a wear-resistant layer of elastomer 40 as the outermost layer surrounding the sole, within which the sole proper 42 made of foamy, flexible polyurethane is attached to the upper 41 of the shoe by gluing. Additionally, the toe of the shoe is provided with a reinforcement layer 43 which is usually formed of split leather. This reinforcement layer 43 improves the durability of the sole in the area covered by the reinforcement, but does not eliminate the criticality of the zone where the edge of the sole meets the upper of the shoe.
Due to the above phenomenen, a problem shared by all footwear on the market intended for ball games or athletic activities, is weakness of the toe portion of the shoe. Experience has shown that even the most expensive and best tennis shoes last no longer than fifty hours of intensive playing, before breaking down of the toe portion of the shoe.